Portable heat gun

ABSTRACT

The forward end of a tubular air discharge spout of a portable air blower is encompassed by a tubular collar supported in spaced relation thereto to form an annular channel for flow of ambient cooling air between the collar and spout. A heater tube having a flared aftersection is positioned in registry with the discharge spout to receive air from the channel and spout. The flared end is secured to the forward end of the collar and has a plurality of apertures through which a portion of the air discharges into an annular air passage formed by a tubular shield encompassing the heater tube in concentric spaced relation. The remainder of the air passes through the heater tube and is heated by an electric heater in the tube. The unheated air energizing from the forward end of the annular air passage encompasses the hot air outflow from the heater tube. The volume and temperature of the air discharge is regulated by an adjustable damper on the blower inlet. A switch enables the user to deenergize the heater, thereby affording a controllable airflow at ambient temperature.

United States Patent Robert C. Berryman 78S Lyyski Street, Sparks, Nev. 89431; Robert R. Townsend, 31 Smithridge Park, Reno, Nev. 89502 [21] Appl. No. 881,680

[22] Filed Dec. 3, 1969 [45] Patented Oct. 12, 1971 {72] Inventors [54] PORTABLE HEAT GUN 3 Claims, 5 Drawing Figs.

[52] US. Cl 219/370, 34/97, 219/367, 219/373, 219/374 [51] Int. Cl 1105b 1/00, F24h 3/04 [50] Field of Search 219/369,

3,209,988 10/1965 Foxetal... 3,219,797 11/1965 Brady Primary Examiner-A. Bartis Attorney-Lothrop & West 219/370 UX 219/373 X ABSTRACT: The forward end of a tubular air discharge spout of a portable air blower is encompassed by a tubular collar supported in spaced relation thereto to form an annular channel for flow of ambient cooling air between the collar and spout. A heater tube having a flared aftersection is positioned in registry with the discharge spout to receive air from the channel and spout. The flared end is secured to the forward end of the collar and has a plurality of apertures through which a portion of the air discharges into an annular air passage formed by a tubular shield encompassing the heater tube in concentric spaced relation. The remainder of the air passes through the heater tube and is heated by an electric heater in the tube. The unheated air energizing from the forward end of the annular air passage encompasses the hot air outflow from the heater tube. The volume and temperature of the air discharge is regulated by an adjustable damper on the blower inlet. A switch enables the user to deenergize the heater, thereby affording a controllable airflow at ambient temperature.

PORTABLE HEAT GUN The invention relates to improvements in portable hot air blowers of the high thermal capacity type.

The market place as well as the patent literature is replete with portable hot air blowers capable of being oriented so as to afford a supply of warm air in a given direction. Exemplary of such devices are those utilized by hair stylists in the course of drying and shaping the customers hair, it being important in this environment that the air temperature and velocity be maintained within reduced limits. At the other extreme are devices of the blowtorch variety, such as are used by plumbers and tile floor layers, wherein the temperature is high enough to melt solder, or to render pliable floor tiles of the rubber, vinyl and asphalt varieties. Intermediate the two foregoing types of mechanisms are blowers which can be moved from place to place, if required, and which can be utilized as space heaters or as atmospheric (temperature and humidity) modifiers.

So far as is known, however, none of the portable devices heretofore available have possessed the capability of providing a stream of air which can be nicely regulated as to temperature as well as selectively afl'ording either a very highcapacity or a very low-capacity air flow.

It is therefore an object of the invention to provide a portable air blower in which the temperature of the discharging air can be controlled over a wide temperature range.

It is another object of the invention to provide a heated air blower which is light in weight, compact in size and is readily manipulated so as to afford close directional control, characteristics which suggest the title "heat gun used herein.

It is yet another object of the invention to provide a portable heat gun which is safe in use in that no flame is used and heat shield members are provided to protect the user against the heat of the electrical heating coils.

It is a further object of the invention to provide a portable heat gun which is relatively economical, both as to initial cost and upkeep, yet which is rugged, versatile'and reliable under a wide variety of uses and environments.

It is another object of the invention to provide a generally improved portable heat gun.

Other objects, together with the foregoing, are attained in the embodiment described in the following description and illustrated in the accompanying drawings in which:

FIG. I is a perspective view of one side of the gun;

FIG. 2 is a perspective view of the other side of the gun;

FIG. 3 is a fragmentary view, to an enlarged scale, of the nozzle, heating element and heat shield, portions being shown in median sectional view;

FIG. 4 is a transverse sectional view of FIG. 3, the plane of the section being indicated by the line 4-4 in FIG. 3; and,

FIG. 5 is a wiring diagram.

While the portable heat gun of the invention is susceptible of numerous physical embodiments, depending upon the environment and requirements of use, substantial numbers of the herein shown and described embodiment have been made, tested and used, and all have performed in an eminently satisfactory manner.

The heat gun of the invention, generally designated by the reference numeral 12, comprises a frame 13, or base, supported on resilient supports 14. Mounted on the frame is a box 16 serving to house a 3-way toggle switch 17 movable from a centralOFF" position to either a left-hand COLD position or a right-hand HOT position, as appears most clearly in FIGS. 1 and 2.

Leading into the housing 16 is power cable 18 connected to a suitable electrical energy source (not shown) by the customary plug 19 (see FIG. 5).

The power cable 18 contains in addition to a ground wire 21 (see FIG. 5) a bus 22 and a return wire 23. More particularly, the bus 22 is connected to the switch terminal 32 and the return 23 is attached to the switch terminal 33.

When the switch lever 17 is in intermediate position all circuits are open.

When the switch 17 is moved to l-IOT" position, two circuits are actuated. One circuit is the motor drive circuit comprising a pair of conductors 28 and 29 connected at one end to an electrical motor 31 mounted on the housing 16 and at the other end to respective switch terminals 32 and 26. The other circuit which is actuated when the switch 17 is moved to HOT position is a heater circuit including a pair of conductors 34 and 36 connected, respectively, to the switch terminals 24 and 33 and to a resistive-type heater 35.

As can be seen most clearly in FIG. 5, movement of doublepole switch 17 into HOT position closes the circuit extending from the plug 19 through conductor 22 to terminal 32. At terminal 32 the current divides, a first portion flowing through conductor 28 to the motor 31, and a second portion shunting through the terminal 24 and thence to the associated arm of the switch 17 to the conductor 34 to one side of the electrical heater 35.

The motor return wire 29 connects to the switch terminal 26 from which point it connects through the switch lever 17 to terminal 33 and return wire 23 to the plug 19.

In similar fashion, the heater return wire 36 connects to the switch terminal 33 and wire 23, and thereby completes the circuit.

In the event it is desired to blow unheated air, the switch 17 is moved to COLD" position. As can be seen by reference to FIG. 5, the effect of this movement of the switch is to actuate only the motor circuit.

In other words, with the switch in "COLD" position, the current from conductor 18 and terminal 32 is led to motor circuit conductor 28. The motor return circuit is established by conductor 29, and junction 26, thence through switch 17 to terminal 48 and return conductor 47, junctions 46 and 30 and conductor 23 to plug 19.

As appears most clearly in FIG. 3, the air heater 35 is located within a nozzle member 50 mounted on the discharge spout 51 of a scroll casing 52, or housing, of a blower 53, comprising a rotor 54 suitably connected to and driven by the motor 31.

Support of the gun and accurate orientation of the nozzle 50 is afforded by a quadrant-shaped handle 56 (see FIGS. 1 and 2) suitably connected at one end by a fastener 57 to a vertical, fore and aft frame plate 58 and at the other end by fasteners 59 to a transverse gusset plate 61.

A handle cover 62 is selected of a material such that it will afford thermal, vibrational and electrical insulation.

With particular reference to FIGS. 3 and 4 it will be noted that the nozzle member 50 comprises a generally tubular structure termed a heater tube 66 having a divergingly flared after portion 67 arranged for registry with the forward end of the scroll spout 51 so as to receive the discharge from the blower and direct the airflow forwardly over the electrical heating coils 35 located in the central portion of the heater tube 66.

A sleeve 71 of mica is mounted on the inner walls of the heater tube 66 and provides insulation from the heating coils 35.

The heater tube 66 nevertheless becomes quite hot during extended use of the coils, and in order to prevent the user from being burned, a tubular shield member 73 is arranged concentrically with respect to the heater tube 66 and is spaced radially outwardly from the heater tube to define an annular chamber 74, or passageway, through which cooling air is driven.

A plurality of apertures 76 is provided in the flared after portion 67 of the heater tube 66; and through these apertures 76 flows a portion of the relatively cool air emerging from the spout 51 of the blower scroll 52. This cooling air then proceeds forwardly through the annular passageway 74, cooling the heater tube 66 and the shield 73 en route, and ultimately discharges from the forward end of the annular passageway 74, thereby joining and comingling with the main body of very hot air discharging from the forward end of the heater tube 66.

A wire screen mesh 77 covers the open end of the nozzle 50 in the interests of safety.

The forward end of the heater tube 66 is supported by a clip member 81 which is roughly triangular in elevation (see FIG. 4) but with the angles of the triangle being truncated. The clip 81 is conveniently formed from springy metal strap material and snugly confines the forward end of the heater tube. At the same time, the clip 81 is itself snugly confined by the tubular outer shield 73.

The flared afterend of the heater tube 66 is secured, as by welding, to the inside surface of an angular transition portion 83 at the afterend of the heat shield 73.

The transition portion 83 merges into an after collar portion 84 which encompasses the spout portion 51 of the blower.

In order to provide thermal insulation between the nozzle 50 and the spout 51, and annular spacing 86, or channel, is provided. The annular channel is defined by the inner surface of the tubular collar 84 and by the outer surface of the adjacent tubular spout 51. The spacing between the collar 84 and the spout 51 is established by a plurality of conventional J- nuts and attendant spring lock washers 87 and machine screws 88 located around the periphery of the spout 51.

As air discharges from the blower spout 51 at a relatively high velocity, air is drawn in, by injection, from the outside,

in the manner indicated by the arrow 89; and upon emerging from the annular channel 86 the air stream mingles with the high-velocity blower air.

The heating element 35 can be of any suitable configuration provided the desired electrical and thermal requirements are attained.

In the form of heater 35 shown most clearly in H08. 3 and 4, an elongated ceramic plate 91 is arranged in a fore-and-aft direction and in a vertical attitude. The forward end portion 92 of the ceramic plate 91 is flared and terminates in a forward upper tip 93 and a forward lower tip 94 lodged, respectively, in a fore-and-aft slot 95 and a fore-and-aft slot 96 formed in an upper dimple 97 and a lower depression, or dimple 98 (see FIGS. 3 and 4) formed in the forward end of the heater tube 66.

The after end of the ceramic plate 91 is held in place by a split ring 99 formed of spring metal strapping, a fastening serving to secure the ceramic plate 91 to an indented portion 102 of the ring 99. Terminal lugs 106 and 107 connect the conductors 34 and 36, respectively to the heating coils 108 via appropriate connecting wires 109 and 110. The specific wiring of the heating element 35 forms no direct part of the invention herein, is considered within the purview of those skilled in the art and thus is neither shown nor described in detail.

In order to control the temperature of the hot air discharging from the nozzle during the HOT mode of operation, a temperature controlling mechanism 121 is afforded (see FIG. 2). This mechanism comprises a damper 122 including a segment plate 123 pivoted at its lower end on a pin 124. An outwardly bent forward lip 126 and afterlip 127 afford convenient finger holds when it is desired to pivot the damper plate 123, or gate, to the desired angular position.

The gate 123 slides on the underlying outer surface of the blower casing and serves selectively to cover and uncover, partially or completely, the air intake opening 131 formed in the blower casing. With the gate 123 swung out of the way, so that no portion of the opening 131 is covered, a large volume of ambient air is acted upon by the blower and the air discharging from the nozzle is consequently at a minimum heated temperature. With the opening 131 substantially entirely covered, on the other hand, a very small amount of relatively cool ambient air is blown over the heating coils, the

result being that this relatively small volume of air is heated to a very high temperature.

Intermediate gate positions can be calibrated so that, as appears in FIG. 2, any desired nozzle discharge temperature, within limits, can be attained by swinging the gate 123 until the indicator arrow 133 is opposite the desired one of the temperature indicia 134.

After switching the toggle 17 from OFF to the desired mode of operation, either COLD" or HOT," the user can conveniently pick up the gun" 12 and, by directing the nozzle 50 toward the work area, can immediately commence operations. The quadrant shape of the handle 56 readily enables the nozzle to be played up and down in a vertical arc while it can also be swung from side to side. A careful control of movement is thereby afforded.

In the event the HOT mode of operation is desired, such as for softening floor tile, the heat regulator 12! is adjusted to provide the appropriate temperature, e.g. 300 F. Where a higher temperature is required, in order to melt solder, for example, it is only necessary to swing the gate to the indicia corresponding to the temperature needed.

It can therefore be seen that we have provided a portable heat gun which is not only safely and conveniently maneuverable to afford a directional stream of hot or cool air, but which is also capable of nicely controlling the temperature of the air stream.

What is claimed is:

1. A portable heat gun comprising:

a. a frame;

b. an air blower mounted on said frame including a rotor and a casing having an air intake port and a tubular air discharge spout to direct air forwardly in a predetermined direction;

c. a tubular collar mounted on and encompassing the forward end of said tubular spout in spaced relation to define a substantially annular channel for the flow of ambient air therethrough;

d. a forwardly converging frustoconical member mounted on the forward end of said tubular collar and having a plurality of apertures extending through the converging walls of said member in said forward direction;

e. a heater tube mounted on the forward end of said converging member, said tube extending forwardly to a hot air discharge end;

f. electrical heating means mounted in said heater tube for heating the air entering said tube from said blower discharge spout and said annular channel less the air flowing through said apertures; and,

g. a tubular shield encompassing said heater tube and forming therewith an annular passageway for the flow therethrough of air passing through said apertures and moving forwardly in said predetermined direction to emerge from the open forward end of said passageway in an annular flow pattern encompassing the hot air emitted from said air outflow from said heater tube, the air flow from said discharge spout being effective to induce the flow of ambient air through said annular channel and along the adjacent surface of said apertured frustoconical member, said ambient air flow helping to maintain the temperature of said tubular collar at ambient conditions. 2. A portable heat gun as in claim 1 wherein said tubular shield member is mounted on the after end of said frustoconical member adjacent the forward end of said tubular collar and in thermal contact therewith.

3. A portable heat gun as in claim 2 further including switch means for disconnecting said electrical heating means. 

1. A portable heat gun comprising: a. a frame; b. an air blower mounted on said frame including a rotor and a casing having an air intake port and a tubular air discharge spout to direct air forwardly in a predetermined direction; c. a tubular collar mounted on and encompassing the forward end of said tubular spout in spaced relation to define a substantially annular channel for the flow of ambient air therethrough; d. a forwardly converging frustoconical member mounted on the forward end of said tubular collar and having a plurality of apertures extending through the converging walls of said member in said forward direction; e. a heater tube mounted on the forward end of said converging member, said tube extending forwardly to a hot air discharge end; f. electrical heating means mouNted in said heater tube for heating the air entering said tube from said blower discharge spout and said annular channel less the air flowing through said apertures; and, g. a tubular shield encompassing said heater tube and forming therewith an annular passageway for the flow therethrough of air passing through said apertures and moving forwardly in said predetermined direction to emerge from the open forward end of said passageway in an annular flow pattern encompassing the hot air emitted from said air outflow from said heater tube, the air flow from said discharge spout being effective to induce the flow of ambient air through said annular channel and along the adjacent surface of said apertured frustoconical member, said ambient air flow helping to maintain the temperature of said tubular collar at ambient conditions.
 2. A portable heat gun as in claim 1 wherein said tubular shield member is mounted on the after end of said frustoconical member adjacent the forward end of said tubular collar and in thermal contact therewith.
 3. A portable heat gun as in claim 2 further including switch means for disconnecting said electrical heating means. 